This application is based upon and claims the benefit of priority of Japanese Patent Applications No. H.10-241500 filed on Aug. 7, 1998 and No. H.11-143309 filed on May 24, 1999, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a wiper device having a wiper motor and link module to be easily and accurately fixed to a vehicle body.
2. Description of Related Art
In a conventional wiper device for wiping a wind shield glass of a vehicle, rain drops are wiped off the wind shield glass by a given range reciprocating movement of a wiper arm attached to a pivot shaft according to the movement of the 20 pivot shaft. A wiper bracket constituting a pivot holder rotatably supports the pivot shaft. The wiper bracket is fixed by a fastening bolt to the vehicle body (for example, a cowl panel arranged beneath the wind shield glass).
In particular, JP-A-9-175336 discloses a wiper device having a wiper motor and link module in which, in a vehicle having a pair of wiper arms and blades, a pair of the wiper brackets for supporting each of pivot shafts are fixed respectively to both width sides of the vehicle body and integrated with a frame for supporting a wiper motor and so on. In the wiper device, another bracket is fixed by welding to the frame connecting the pivot holders (wiper brackets) and the wiper motor is fixed on the bracket.
The wiper device having the wiper motor and link module according to the construction mentioned above is relatively simple and compact. The wiper device is generally fixed to the vehicle body by at least three fastening bolts to be inserted respectively into three installation holes, two for the pair of pivot holders and one for the bracket.
In case of fastening and fixing the wiper device to the vehicle body at three points such as two for the pivot holders and one for the bracket, the fixing positions are forced to be determined exactly at the three points and, if there exists a discrepancy due to fabrication errors between the installation positions of the wiper device (pivot holders and so on) and those of the vehicle body, an adjustment of the three points becomes necessary. For this purpose, one or more of the installation holes (for example, two installation holes) of the wiper device are provided with long narrow shaped cross sectional holes or larger so called loose holes which make a slight adjustment available.
However, in such a case, the adjusting work for fixing accurately the wiper device to the vehicle body is so complicated that the installation work productivity may be inadvertently affected. Further, the fastening work needs more time and more number of fastening parts are required because the wiper device is fixed to the vehicle body in a manner that the three fasteners such as bolts are inserted into and fastened to the three installation holes, respectively.
The present invention has been made in view of the above mentioned problem, and an object of the present invention is to provide a wiper device which may be fixed accurately to given positions of the vehicle body with an easy slight adjustment of the installation position, resulting in shorter time for fastening work and smaller number of fastening parts.
To achieve the above object, the wiper device has a motor and link module to be fixed to a vehicle body. The motor and link module are composed of a frame, a wiper motor for generating a driving force fixed to the frame and provided with a supporting pin to be inserted into and held by a hole of the vehicle body, a pair of pivot shafts, a pair of pivot holders, each of which has a fastening portion to be fastened and fixed to the vehicle body, for rotatably supporting each of the pivot shafts respectively fixed at both ends of the frame and a link mechanism connecting the motor and each of the pivot shafts for transmitting the driving force of the motor to each of the pivot shafts, wherein a gravity force at a gravity center of the motor is exerted to cross a territorial region surrounded by positions of the supporting pin and the respective fastening portions of the pivot holders.
According to the wiper device mentioned above, the wiper motor and link module that the pivot shafts, the pivot holders, the frame, the motor and the link mechanism are integrated in advance into an assembly is fixed to the vehicle body. The supporting pin of the wiper motor is at first inserted into and held by the hole of the vehicle body to decide a fixing position of the module as a reference position and, then, the fastening portions of the pivot holders are fixed to the vehicle body.
The reference position for fixing the module to the vehicle body is decided only by inserting the supporting pin into the hole and the module is held at the position by the pin and the hole. This makes the fixing of the module to the vehicle body very easy.
Further, if there is a discrepancy between the installation positions of the module and those of the vehicle body, the supporting pin may be slightly moved back in an inserting direction to the hole without shifting the reference position thereof for an adjustment purpose when the fastening portions of the pivot holders are fastened and fixed to the vehicle body. Therefore, the fixing work including the slight adjustment of the fixing positions may be easily conducted in shorter time.
Furthermore, as a gravity force at a gravity center of the motor crosses a territorial region surrounded by positions where the supporting pin and the respective fastening portions of the pivot holders are located, a heavy weight of the motor and the like may be adequately shared with the holding and fixing points so that a force against the supporting pin may become smaller and the possible break down of the supporting pin may be effectively prevented.
The wiper motor is provided with a fixing base at a side thereof where the motor is fixed to the frame and with the supporting pin at a side opposite to the fixing base so that the relatively heavy motor may be supported with an adequate weight balance by the frame and the supporting pin.
Further, as the supporting pin is protruded from the wiper motor in a direction far from a line connecting the respective fastening portions of the pivot holders, the wiper motor is effectively installed on the module so that the gravity force at a gravity center of the motor may cross a region surrounded by positions where the supporting pin and the fastening portions of the pivot holders are located.
Though the relatively heavy wiper motor is arranged at one side of a straight line connecting the respective fastening portions of the pivot holders, a moment operative around the straight line may be eased by allocating the weight of the wiper motor to the supporting pin located far away from the straight line so as to constitute a triangle by the supporting pin and the two fastening portions of the pivot holders.
The supporting pin is provided with a stopper so that the supporting pin may be simply inserted into the hole of the vehicle body until the insertion of the pin is restricted. Once the module is inserted into the hole, the position of the module to the vehicle body is held as the reference position. As a result, an easy and accurate fixing operation can be secured without skill.
The supporting pin is inserted through a bush into the hole of the vehicle body. The bush is made of elastic material such as rubber and has a cylindrical portion and a flange portion provided at an end of the cylindrical portion. An outer circumference surface of the cylindrical portion is fitted into the hole. The supporting pin is inserted through an inner circumference of the cylindrical portion and the flange portion is in contact with a periphery around the hole. Therefore, the bush absorbs the vibration occurred when the motor is driven so that the transmission of the vibration through the supporting pin and the hole to the vehicle body may be prevented. Further, the bush prevents vibration noises that may be generated, if the supporting pin were directly in contact with the periphery of the hole.